"I am looking forward to playing my role in driving success for both Leinster and Ireland."
The Naas man made his senior debut for Leinster against the Ospreys in March 2005 and has since made 176 appearances for Leinster, scoring 34 tries.
He made his Ireland debut in the 61-17 win over the Pacific Islanders in November 2006. The 30-year-old has won 60 caps for Ireland to date, scoring eight tries.
His last appearance for Ireland was in the 22-20 loss to New Zealand in November.
Heaslip has twice toured with the British & Irish Lions in 2009 and 2013, playing in five Tests. He has won a Grand Slam with Ireland as well as three Heineken Cups, an Amlin Challenge Cup and two league titles with Leinster.
He was shortlisted for the IRB Player of the Year award in 2009 and for the ERC Player of the Year award in 2013.
IRFU Chief Executive Philip Browne commented: "We are delighted that Jamie has committed his future to Leinster and Ireland for the next three years.
"He has been one of the most consistent performers and top number 8s in world rugby for many years and has played a starring role for Leinster, Ireland and the Lions."
Leinster Chief Executive Mick Dawson added: "We are delighted that Jamie has signed a new IRFU contract which keeps him at Leinster up to the end of the 2017 season.
"Jamie has played a massive role in Leinster's success over the past six or seven years, he is a key leader within the squad and he will play an integral part in our plans to compete for silverware in the years to come."